I think Thor means that not everyone takes the time to join the same TS server, but if a second voice comms interface was integrated into the game and joined automatically when you join the server, you would still be able to talk to everyone regardless of whether they had joined different TS servers in the background.
Now that i think of it, a combination of both would also help a lot to filter unwanted information. So for example, i could be flying with my regular group/squad and talk to them via our TS server, but i wouldn't have to alt+tab, join a different one and alt+tab back in the game to request a "clear my six" to someone who was on a different TS server. If it was modelled like a real radio i wouldn't have to worry about adding to the confusion so much either, as the only people who would hear me would be the ones close to my part of the map